<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			/* 交集选择器 */
			div.myClass{
				height: 100px;
				background-color: red;
			}
			/* 并集选择器 */
			span,a{
				color: red;
			}
		</style>
	</head>
	<body>
		<div class="myClass">DIV</div>
		<div></div>
		<h1 class="myClass"></h1>
		<h1></h1>
		<span>SPAN</span>
		<a href="https://www.baidu.com">百度</a>
	</body>
</html>
